The role of colloids on the bioavailability of phosphate to plants in highly weathered soils.
This Ph.D. addresses a concept that may lead to the development of a new type of phosphate (PO4) fertiliser. That fertiliser is based on nanoparticles of aluminium or iron oxides, coated with PO4. These nanoparticles act as mobile carriers of PO4 in soil, thereby avoiding that PO4-ions are trapped and fixed in soil minerals. Low phosphorus (P) availability is one of the most important plant nutritional problems in strongly weathered soils. Recently, it was shown that supplementing a low-P nutrient solution with Al2O3 nanoparticles, coated with PO4, enhances P bioavailability to plants. This study will assess if the same is true in weathered soils where the same process already occurs naturally, albeit that colloidal P is naturally present at low concentrations. The objective of this study is to reveal the role of colloidal P on P uptake to plants and to design engineered nanoparticles to enhance P uptake.
We speculate that PO4 loaded nanoparticles will enhance PO4 mobility and bioavailability compared to equal doses of PO4 added to the same soil as soluble fertiliser P. Soil chemical studies with advanced colloidal characterization methods will be combined with short-term bioassays to address this issue.